1. Field of the Invention
Embodiments of the invention relate to a structure for mounting a flexible circuit for transmitting scan signals or data signals in a display device.
2. Discussion of the Related Art
Various flat panel displays such as a liquid crystal display (LCD), a plasma display panel (PDP), an organic light emitting display, a field emission display (FED), and an electrophoresis display (EPD) have been developed.
Driver integrated circuits (ICs) of the flat panel display are mounted on a display panel and are connected to data lines (or signal lines) or scan lines (or gate lines). A source driver IC supplies a data signal to the data lines, and a gate driver IC sequentially supplies a scan signal (or a gate pulse) synchronized with the data signal to the scan lines.
To mount the driver ICs on the display panel, a method for bonding a flexible circuit means mounting the driver ICs to the display panel, a chip-on glass (COG) method for directly bonding the driver ICs to a substrate of the display panel, etc. are well known. Examples of the flexible circuit means used to mount the driver ICs include a chip-on film (COF) and a tape carrier package (TCP). In the following description, the COF is used as an example of the flexible circuit means. The flexible circuit means, on which the driver ICs are mounted, is bonded to the substrate of the display panel using an anisotropic conductive film (ACF).
As shown in FIGS. 1 and 2, source COFs 6 and gate COFs 8 are connected to a substrate 2 of a display panel. A source driver IC 5 is mounted on each of the source COFs 6. Output terminals of the source COFs 6 are bonded to the substrate 2 of the display panel, so that they are connected to data lines of the display panel. Input terminals of the source COFs 6 are connected to a source printed circuit board (PCB) 4. A gate driver IC 7 is mounted on each of the gate COFs 8. The gate COFs 8 are bonded to the substrate 2 of the display panel, so that they are connected to gate lines of the display panel. The gated COFs 8 are also bonded to and to a gate PCB (not shown).
When the COFs 6 and 8 are bonded to the substrate 2 of the display panel in a forward direction, the COFs 6 and 8 partially protrude beyond the substrate 2 of the display panel. A method for bonding the COFs 6 and 8 in the forward direction is to bond one end of each of the COFs 6 and 8 to an edge of the substrate 2 of the display panel so that the other end of each of the COFs 6 and 8 faces toward the outside of the substrate 2 of the display panel. Because the COFs 6 and 8 are flexible, the COFs 6 and 8 may be bent as shown in FIG. 2. Examples of the method for bonding the flexible circuit means mounting the driver ICs to the substrate of the display panel in the forward direction to partially protrude the driver ICs to the outside of the substrate are disclosed in Japanese Patent Publication No. Hei 6-231814 (publication date: Aug. 19, 1994), Japanese Patent Publication No. 2003-186044 (publication date: Jul. 3, 2003), U.S. Patent Application Publication No. 2002/0180686A1 (publication date: Dec. 5, 2002), and U.S. Patent Application Publication No. 2004/0169645A1 (Sep. 2, 2004), which are hereby incorporated by reference in their entirety.
After bonding the COFs 6, 8 to the substrate 2 of the display panel, the COFs 6, 8 are bonded to the source PCB 4 or the gate PCB. For this purpose, the COFs 6, 8 are flattened as shown in FIG. 1. Then a bonding tool (not shown) applies heat and pressure to the ends of the COFs 6, 8 not attached to the substrate 2 of the display panel. Because the bonding tool operates to apply heat at the left side or bottom part of FIG. 1 at locations away from the substrate 2, the substrate 2 is not affected by the heat generated by the bonding tool. After the COFs 6, 8 are bonded to the source PCB 4 or the gate PCB, the COFs 6, 8 are flipped over the substrate 2 (the flipping of COF 8 is illustrated in FIG. 2).
As a result flipping the COFs 6, 8 over the substrate 2, the COFs 6 and 8 partially protrude beyond the substrate 2 of the display panel as shown in FIG. 2. As shown in FIG. 2, the portions of the COFs 8 overlap across length OL. Thus, even if the substrate 2 of the display panel does not have a bezel area, a bezel of a display device may not be reduced to the size equal to or less than a protrusion width of the flexible circuit means. Further, the edges of the display panel have to be rounded because of the problem of the design. However, as shown in FIGS. 1 and 2, because a grinder interferes with the gate COFs 8, it is difficult to round a portion of edges 2a and 2b of the substrate 2 of the display panel. Thus, when the COFs 6 and 8 protrude to the outside of the substrate 2 of the display panel, a bezel width of the display device increases and it is difficult to round the edges of the substrate 2 of the display panel.